This invention concerns pressure responsive diaphragms and methods of manufacture thereof, and more particularly such diaphragms which are dish shaped to be able to be forced into a housing cavity during use without substantial stretching of the diaphragm material.
Pressure responsive diaphragms are utilized in a great number of applications for accomplishing various purposes.
In U.S. Pat. No. 4,430,231 there is disclosed a high pressure industrial filtering apparatus which includes a generally rectangular housing defining a rectangular filtering cavity. A dewatering diaphragm is mounted above the cavity and pressurized at moderately high pressure to force water out of accumulated filter "cake" prior to a cleaning cycle of a filter belt in the filtering cavity.
The diaphragm for such application must be relatively rugged since repeated contact under heavy pressure with filtered solids is entailed, and the diaphragm must be able to be tightly sealed against the filtering and diaphragm operating pressure.
The use of stretchable material to enable movement into the cavity is not practical for such application due to the rugged construction required.
A molded construction is costly, particularly for the relatively great size of such industrial filters.
Fabrication from flat sheet stock has heretofore required seams to be formed at the corners, which seams are subject to failure under these moderately high pressures.
Accordingly, it is an object of the present invention to provide a method of constructing a flanged dish shaped diaphragm from flat sheet material which accommodates movement upon being pressurized and forced into a cavity without significant stretching, but which does not involve corner seams.